The invention relates to an apparatus for producing compost, more particularly from domestic and/or garden refuse or the like, comprising a drum adapted to be driven for rotation about its generally level longitudinal axis and having a circumferential casing which is at least in part formed by perforated sheet metal, a longitudinal conveying device arranged generally parallel to the axis and able to be driven forwards and backwards under the drum for the purpose of conveying material falling out of the drum either to a compost pile or to a lifting conveyor arranged adjacent one end of the drum, and a charging device arranged in the upper part of the drum for cooperation with a lifting conveying device.
The content of the drum is as a rule not homogeneous and will tend to contain fine and coarse particles. The coarse material is in this respect less easy to rot down than the fine material and there is thus the requirement for causing a distribution of the fine and coarse material which is as even as possible. On the other hand the rotating drum tends to cause a division of the material into coarse and fine fractions. It is assumed that the so-called Coriolis acceleration is the cause of this, which leads to zones with a pronounced concentration of the coarse material. The conveying device which is able to be driven forwards and backwards does, it is true, makes possible a return of the material falling out of the drum in cooperation with the lifting conveying device. However, the perforated sheet metal forming the peripheral casing of the drum only sifts out fine material and coarse material is retained in the drum so that in the coarse of time there is a pronounced collection of coarse material in the drum to be expected, more especially since this material, as already noted, is difficult to rot down. The result is that the rate of processing of the material through the apparatus is considerably reduced. In the case of the coarse material it generally turns out to be adhering lumps of rotting material. These lumps are very difficult to rot down owing to their consistency and may thus greatly impair the rotting process, more especially if there is a high local concentration of such lumps.